[ischmitz]

I agree with almost everything mysocal911 says; the “modern designs” are a poor solution in search of a problem. Their designs lack in reliability and add unnecessary complexity. If modern engine control units were designed and built to these standards I’d invest into a tow truck service because roadways would be littered with broken-down cars.

However, there is one exception. Bosch boxes do require rebuilding once the main capacitor is sufficiently aged and worn or shorted. Aside from over-voltage that is their dominant failure mode. In some boxes I get in the capacitor shows memory effects, severe leakage and becomes part ohmic once at temperature. This further accelerates aging and replacing the capacitor addresses that issue.

Interestingly 6-pin boxes have a significantly higher capacitor failure rate compared to the older 3-pin versions even though it’s the same part. My theory is that 6-pin boxes in later cars are exposed to higher average engine bay temperatures resulting in accelerated wear rates.